EBS is a block storage device that attaches to a single EC2 instance in one Availability Zone, while EFS is a managed network file system that can be simultaneously shared across thousands of EC2 instances in multiple Availability Zones. EBS offers higher performance and lower latency, while EFS offers shared access, automatic scaling, and built-in high availability.
EBS and EFS are both persistent AWS storage services for EC2 instances, but they solve fundamentally different problems. EBS is a high-performance block device — think of it as a virtual hard drive dedicated to one instance. EFS is a shared network file system — think of it as a shared NAS (Network Attached Storage) drive accessible by any number of instances simultaneously. Choosing between them depends on whether your workload needs shared access, automatic scaling, or raw I/O performance.
EBS — Block storage. Accessed as a raw block device (/dev/xvdf). Must be formatted with a file system (ext4, XFS). Uses local device protocol (not network file system).
EFS — File storage. Accessed over NFS (Network File System) protocol v4.0/4.1. Already has a managed POSIX file system — no formatting needed.
EBS — Can only be attached to ONE EC2 instance at a time (exception: io1/io2 Multi-Attach supports up to 16 instances in the same AZ with a cluster-aware file system).
EFS — Can be simultaneously mounted by THOUSANDS of EC2 instances across multiple Availability Zones and even on-premises servers.
EBS — Locked to a single Availability Zone. To use across AZs, you must snapshot and create a new volume in the target AZ.
EFS — Regional service (Standard class). Accessible from all AZs in the same region via Mount Targets in each AZ. EFS One Zone is restricted to a single AZ.
EBS — Fixed size. You must pre-provision capacity (e.g., 100 GiB, 500 GiB). You can increase the size later (Elastic Volumes), but you cannot shrink it. Costs are based on provisioned size.
EFS — Fully elastic. Automatically grows and shrinks as files are added and removed. No pre-provisioning. You pay only for storage actually used.
EBS (gp3) — Up to 16,000 IOPS and 1,000 MiB/s throughput. Sub-millisecond latency. Consistent, predictable performance.
EBS (io2 Block Express) — Up to 256,000 IOPS and 4,000 MiB/s. Best block storage performance available.
EFS (General Purpose) — Sub-millisecond metadata latency. Up to 35,000 IOPS. Up to 3 GiB/s read / 1 GiB/s write with Elastic Throughput.
EFS adds network latency compared to EBS since all I/O travels over the network — EBS is faster for single-instance, low-latency workloads.
EBS — Supports both Linux and Windows EC2 instances.
EFS — Supports Linux ONLY. For Windows shared file storage, use Amazon FSx for Windows File Server.
EBS gp3 — ~$0.08 per GB-month (provisioned, regardless of usage)
EBS io2 — ~$0.125 per GB-month + $0.065 per provisioned IOPS-month
EFS Standard — ~$0.30 per GB-month (pay for actual usage)
EFS Standard-IA — ~$0.025 per GB-month (pay for actual usage + retrieval fee)
EBS is cheaper per GB for dedicated single-instance workloads. EFS is cost-effective for shared workloads especially when combined with IA lifecycle policies.
Use EBS when: you need a root/boot volume, a high-performance single-instance database (MySQL, PostgreSQL, MongoDB), a dedicated application volume with maximum IOPS, or Windows file storage
Use EFS when: multiple EC2 instances need to share the same files simultaneously, you need shared web content for instances behind a load balancer, you are building a content management system or media processing pipeline, you want automatic capacity scaling without pre-provisioning
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